Conventionally, a coated cutting tool formed by depositing, through chemical vapor deposition, a coating layer with a thickness of from 3 μm or more to 20 μm or less onto a surface of a substrate comprised of a cemented carbide, is well known for being used for the cutting of steel, cast iron, etc. An example of the above coating layer is a coating layer comprised of a single layer of one kind selected from the group consisting of a Ti carbide, a Ti nitride, a Ti carbonitride, a Ti carboxide, a Ti carboxynitride and aluminum oxide, or comprised of multiple layers of two or more kinds selected therefrom.
Patent Document 1 discloses a cutting tool in which, on a surface of a tool substrate made of a WC group cemented carbide or TiCN group cermet, a Ti compound layer is formed as a lower layer and an Al2O3 layer is provided as an upper layer, the Al2O3 layer having an α-type crystalline structure and showing an X-ray diffraction chart which shows clear diffraction peaks on a (006) plane and a (018) plane in an X-ray diffraction measurement.